Estimation of serum M-protein concentration from polyclonal immunoglobulins: an alternative to serum protein electrophoresis and standard immunochemical procedures.

Background: Serum monoclonal proteins (M-proteins) are usually quantified by electrophoresis or immunochemical measurement. A third alternative involves immunochemical measurement of the monoclonal isotype by subtraction of the polyclonal part of the isotype calculated from the other polyclonal isotypes and light chain. We experimentally calculated heavy chain/light chain equivalence factors for three immunoglobulin (Ig) isotypes and compared serum M-protein concentrations obtained using the three approaches.

Retrospective study of monoclonal gammopathies detected in the clinical laboratory of a Spanish healthcare district: 14-year series.

Background: We studied the incidence, classification and isotype distribution of monoclonal gammopathies and M-protein detected between 1992 and 2005 inclusive in the clinical laboratory of a healthcare district in Madrid (Spain) with an average population of 280,574 inhabitants.

Methods: Serum electrophoresis was carried out on a cellulose acetate support up until 1997, and then using capillary zone electrophoresis systems, with M-protein identification carried out by agarose gel immunofixation. The age-adjusted incidences were standardized with respect to the WHO World Standard Population Distribution, based on the world average population between 2000 and 2025.

Linearity and detection limit in the measurement of serum M-protein with the capillary zone electrophoresis system Capillarys.

We studied the linearity and detection limits of the capillary zone electrophoresis system Capillarys in the measurement of serum monoclonal protein. Three monoclonal proteins with different isotypes and electrophoretic migrations were diluted with a hypo-gamma-globulinemic polyclonal serum pool. Mathematical linearity was observed for all monoclonal protein isotypes in the ranges studied without removing the polyclonal gamma-globulin background.

The predictive power of serum kappa/lambda ratios for discrimination between monoclonal gammopathy of undetermined significance and multiple myeloma.

The predictive power of serum kappa/lambda ratios on initial presentation of immunoglobulin G (IgG) or IgA monoclonal component was studied to differentiate between monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM) patients. The retrospective study involved 145 patients clinically diagnosed with monoclonal gammopathy of undetermined significance or multiple myeloma, who had serum M-protein IgG <35 g/L or IgA <20 g/L at M-protein detection. Serum light chains kappa and lambda were measured by fixed-time nephelometry.

Classification of renal proteinuria: a simple algorithm.

Total protein, albumin, alpha1-microglobulin, and immunoglobulin G (IgG) were analyzed in 1,622 urine samples without Bence-Jones proteinuria or gross hematuria. There was correlation with the histological picture obtained on renal biopsy in 61 patients. We established 24-h reference intervals for alpha1-microglobulin and IgG on 659 urine samples with total protein and albumin excretion rates below 100 mg/24 h and 30 mg/24 h, respectively, and creatinine clearance above 80 ml/min.